Several critics have suggested that Crichton uses the major characters as proxies for differing viewpoints on the topic of global warming in order to allow the reader to clearly follow the various positions portrayed in the book.
- Joseph Romm suggests that Kenner is a stand-in for Crichton himself.
- David Roberts suggests that Evans is the stand-in for the reader (who Crichton presumes accepts most of the tenets of global warming without any detailed study of it, but not unquestioningly) and also that Ted Bradley is a stand-in for people who accept the "environmentalist" party line without question.
- Ronald Bailey suggests that Drake is a stand-in for the environmental movement "professional" activist.
- Bruce Barcott suggests that Sarah, and Michael B. McElroy and Daniel P. Schrag suggest that Jennifer are stand-ins for the academic community (intelligent enough to follow the debate but undecided until the evidence is presented) with Sarah being the portion of the community likely to believe in global warming on less than undeniable evidence (they will accept "Likely, but not proven" as sufficient proof) and Jennifer representing the part of the community that accepts undeniable evidence only.
- Michael B. McElroy and Daniel P. Schrag also suggest that Jennifer is simultaneously a stand-in for conflicts of interest created by how the research is funded (i.e. her "official" story changes based on who is paying the bills but in private she makes her true feelings known).
- Gregory Mone suggests that Sanjong is a stand-in for the local university library/reputable Internet source verification, etc.
